Layer Sequence Optimization in Graded Aluminum Foam for Enhanced Impact Energy Absorption

This study investigates the energy absorption behavior of gradient aluminum foam under impact loading, with emphasis on the effects of layer sequencing and loading wavelength. A Voronoi-based modeling technique was developed to generate aluminum foam models with controlled porosity and validated experimentally using split Hopkinson pressure bar tests. Numerical models of foams with varying densities were assembled into gradient configurations and subjected to impact loads across a range of dimensionless wavelengths. Results demonstrate that the energy absorption rate decreases with increasing wavelength, with the most significant reduction occurring in the wavelength range of 4–7. The negative gradient configuration (HML) achieved the highest absorption rate, outperforming the positive gradient (LMH) by a considerable margin, particularly under shorter wavelengths. The layer adjacent to the impact side was identified as the dominant factor governing energy absorption performance. The investigation provides guidance for the optimal design of graded aluminum foam structures in impact protection applications.